Memory is a computing term for a system or device that stores data for immediate use in a computer, computer hardware, or other digital electronic devices. The terms main memory and primary storage are frequently used interchangeably. Store is a dated word for memory. “Java.lang.outofmemoryerror: gc overhead limit exceeded” is a common error that many programmers encounter. It happens in many ways. Let’s read this article to find the cause of it and how to fix this error.

When do you get the error “java.lang.outofmemoryerror: gc overhead limit exceeded”?

When you add key-value pairs in a loop that is not unterminated as the following:

public class OutOfMemoryGCLimitExceed {
    public static void addRandomDataToMap() {
        Map<Integer, String> dataMap = new HashMap<>();
        Random r = new Random();
        while (true) {
            dataMap.put(r.nextInt(), String.valueOf(r.nextInt()));
        }
    }
}

You easily can encounter the following error “Java.lang.outofmemoryerror: gc overhead limit exceeded” if you run this command from the root of program:

mvn exec:exec

A subclass of java.lang.VirtualMachineError is called OutOfMemoryError. When the JVM runs into a resource usage issue, it throws this exception. More specifically, the problem happens when the JVM overran its garbage collection process and was only able to recover a very little amount of heap space. Java documentation states that the JVM is set up by default to raise this error in the case more than 98 percent of Java process time is spent on garbage collection and when fewer than 2 percent of the heap is recovered during each run. In other words, your application has virtually used up all of the memory that is available, and the garbage collector has tried to clean it for an excessive amount of time but failed repeatedly.

Users in this case complain that the application is extremely slow. Some operations, which generally finish in milliseconds, take longer to finish. This is because the CPU is unable to do any other work because Garbage Collection is taking up all of its processing power.

What are the best solutions for fixing error “java.lang.outofmemoryerror: gc overhead limit exceeded”?

Solution 1: Check the code for memory leaks

The best solution for the error “java.lang.outofmemoryerror: gc overhead limit exceeded” is to identify the root cause of the application’s issue by checking the code for memory leaks.

The following inquiries must be answered:

What are the application’s objects that take up the majority of the heap space?

Where are these objects being allocated in the source code?

Solution 2: Temporary or weakly-referenced objects should be avoided

A lot of temporary or weakly-referenced objects should be avoided because they increase the likelihood of memory leakage.

Solution 3: Use automatically generated graphical tools

Additionally, you can use automatically generated graphical tools like JConsole to find performance issues in code, including java.lang. OutOfMemoryErrors.

Solution 4: Check the logs

To verify the error, check the logs.

1. Establish an SSH connection to the master node.
2. To check the health of the NameNode service, issue the command below on the master node:

initctl list

The output shown below shows that the NameNode service has terminated:

hadoop-hdfs-namenode stop/waiting

   3. Let’s examine the NameNode log at the path below to confirm the exception of OutofMemory: /var/log/hadoop-hdfs/hadoop-hdfs-namenode-ip-xxxx.out. Substitute xxxx with the particular IP address of the master node (for instance: /var/log/hadoop-hdfs/hadoop-hdfs-namenode-ip-10-0-1-109.out).

An output like the below confirms that the NameNode service did not work due to an exception of an OutOfMemory:

java.lang.OutOfMemoryError: GC overhead limit exceeded
-XX:OnOutOfMemoryError="kill -9 %p
kill -9 %p

Solution 5: Change the JVM launch parameters to increase the heap size

The last solution for “java.lang.outofmemoryerror: gc overhead limit exceeded” error is to change the JVM launch parameters to increase the heap size. Take a look at the following example:

java -Xmx1024m com.xyz.TheClassName

This provides the Java application with 1 GB of memory space. If the application code itself has memory leaks, this won’t help the situation. You will simply delay the error instead. Therefore, it is more prudent to carefully review the application’s memory consumption.

Conclusion

You may apply our methods when learning how to fix the error “java.lang.outofmemoryerror: gc overhead limit exceeded“. These methods may seem complicated, but they will best solve your issue. You may use the dir(), vars() function, or the pprint module to solve the issue. Please fill in the blanks with questions and suggested responses to help us better assist you. Thank you!

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